Interesting to know... I only use Adwords on our small channel, but I haven't looked carefully at retention for about 2 weeks... you've piqued my curiosity!Our % retention from Adwords has plummeted in the last 2 weeks.
Something has changed, perhaps related to the algorithm update???
Perhaps Google is now sending ads to any viewers, even "low quality" ones (by this I mean viewers with low retention). => Targeting settings are still in place as always, it's just the viewers watch less and drop off quicker.
Or perhaps something else has changed with how Yt works with Google ads, algorithmically.
We've stopped all our ad campaigns now, there is no point paying for low retention views that hurt the video and channel.
If anyone is experiencing something similar, post your details pls, try to understand what is happening.